HIV-1 (human immunodeficiency virus-1) infection remains a major medical problem, with an estimated 42 million people infected worldwide at the end of 2002. The number of cases of HIV and AIDS (acquired immunodeficiency syndrome) has risen rapidly. In 2002, approximately 5 million new infections were reported and 3.1 million people died from AIDS. Currently available drugs for the treatment of HIV include ten nucleoside reverse transcriptase (RT) inhibitors or approved single pill combinations: zidovudine or AZT (or Retrovir®), didanosine or DDI (or Videx®), stavudine or D4T (or Zerit®), lamivudine or 3TC (or Epivir®), zalcitabine or DDC (or Hivid®), abacavir succinate (or Ziagen®), tenofovir disoproxil fumarate salt (or Viread®), emtricitabine (or Emtriva®), Combivir® (contains 3TC and AZT), Trizivir® (contains abacavir, 3TC and AZT); three non-nucleoside reverse transcriptase inhibitors: nevirapine (or Viramune®), delavirdine (or Rescriptor®) and efavirenz (or Sustiva®), eight peptidomimetic protease inhibitors or approved formulations: saquinavir (or Invirase® or Fortovase®), indinavir (or Crixivan®), ritonavir (or Norvir®), nelfinavir (or Viracept®), amprenavir (or Agenerase®), atazanavir (Reyataz®), fosamprenavir (or Lexiva), Kaletra® (contains lopinavir and ritonavir), and one fusion inhibitor enfuvirtide (or T-20 or Fuzeon®).
Each of these drugs can only transiently restrain viral replication if used alone. However, when used in combination, these drugs have a profound effect on viremia and disease progression. In fact, significant reductions in death rates among AIDS patients have been recently documented as a consequence of the widespread application of combination therapy. Despite these impressive results, 30 to 50% of patients ultimately fail combination drug therapies. Insufficient drug potency, non-compliance, restricted tissue penetration and drug-specific limitations within certain cell types (e.g. most nucleoside analogs cannot be phosphorylated in resting cells) may account for the incomplete suppression of sensitive viruses. Furthermore, the high replication rate and rapid turnover of HIV-1 combined with the frequent incorporation of mutations, leads to the appearance of drug-resistant variants and treatment failures when sub-optimal drug concentrations are present (Larder and Kemp; Gulick; Kuritzkes; Morris-Jones et al; Schinazi et al; Vacca and Condra; Flexner; Berkhout and Ren et al; (Ref. 6-14)). Thus, there is continuing need for new compounds and methods of treatment for HIV infection.
1-Benzoyl-4-[2-[4-methoxy-7-(3-methyl-1H-1,2,4-triazol-1-yl)-1H-pyrrolo[2,3-c]pyridin-3-yl]-1,2-dioxoethyl]-piperazine (Compound 1) is an HIV-1 attachment inhibitor demonstrating potent antiviral activity against a variety of laboratory and clinical strains of HIV-1 (see U.S. patent application U.S. 2003 0207910, published Nov. 6, 2003).

Compound 1 acts by selectively preventing attachment of the exterior viral envelope protein gp120 to its cellular receptor CD4. Binding of gp120 to CD4 is the first step in viral entry and is distinct from the subsequent interaction with a chemokine receptor (CCR5 or CXCR4) or virus-cell fusion event. By inhibiting this interaction, Compound 1 blocks viral entrance into cells.